Igmp Basics - Supermicro SSE-G24-TG4 Configuration Manual

IGMP Configuration Guide

1.2 IGMP Basics

IGMP is an IPv4 protocol used by hosts to request multicast data for a particular group. A switch
performs the IGMP function by:
Sending IGMP query messages to identify receivers interested in particular multicast group(s).
•
IGMP queries are sent only by a querier.
Processing IGMP report messages from hosts in response to the query message from the
•
querier.
Switches maintain a multicast forwarding table based on the hosts joined for every multicast group and
updates the multicast forwarding table when hosts leave multicast groups.
In Figure IGMP-2, the querier switch sends an IGMP General Query message on the LAN. Host1 and
Host2 respond to the query with the IGMP report for G1 Group membership.
Figure IGMP-2: Multicast Forwarding with IGMP
Switch - Querier
General Query
Membership
report for G1
Host 1
There are 3 versions of IGMP. The basic differences between the versions are:
IGMP v1: Supports basic query-response mechanism to identify active multicast group(s).
IGMP v2: Extends v1 with features like querier elections, IGMP leaves, group-specific queries and
maximum response time fields.
IGMP v3: In addition to IGMP v1 and IGMPv2 features, provides support for source-specific queries and
reports.
General Query
Host 2
Supermicro L2/L3 Switches Configuration Guide
Switch – Non Querier
Membership
report for G1
Host 3
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